/**
*    Copyright (C) 2013 10gen Inc.
*
*    This program is free software: you can redistribute it and/or  modify
*    it under the terms of the GNU Affero General Public License, version 3,
*    as published by the Free Software Foundation.
*
*    This program is distributed in the hope that it will be useful,
*    but WITHOUT ANY WARRANTY; without even the implied warranty of
*    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
*    GNU Affero General Public License for more details.
*
*    You should have received a copy of the GNU Affero General Public License
*    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*
*    As a special exception, the copyright holders give permission to link the
*    code of portions of this program with the OpenSSL library under certain
*    conditions as described in each individual source file and distribute
*    linked combinations including the program with the OpenSSL library. You
*    must comply with the GNU Affero General Public License in all respects for
*    all of the code used other than as permitted herein. If you modify file(s)
*    with this exception, you may extend this exception to your version of the
*    file(s), but you are not obligated to do so. If you do not wish to do so,
*    delete this exception statement from your version. If you delete this
*    exception statement from all source files in the program, then also delete
*    it in the license file.
*/


#pragma once

#include <boost/scoped_ptr.hpp>
#include <boost/thread/mutex.hpp>
#include <boost/thread/condition_variable.hpp>

#include "mongo/client/constants.h"
#include "mongo/client/dbclientcursor.h"
#include "mongo/util/net/hostandport.h"

namespace mongo {
    class OperationContext;

namespace repl {

    class SyncSourceFeedback {
    public:
        SyncSourceFeedback();
        ~SyncSourceFeedback();

        /// Ensures local.me is populated and populates it if not.
        /// TODO(spencer): Remove this function once the LegacyReplicationCoordinator is gone.
        void ensureMe(OperationContext* txn);

        /// Notifies the SyncSourceFeedbackThread to wake up and send a handshake up the replication
        /// chain, upon receiving a handshake.
        void forwardSlaveHandshake();

        /// Notifies the SyncSourceFeedbackThread to wake up and send an update upstream of slave
        /// replication progress.
        void forwardSlaveProgress();

        /// Loops continuously until shutdown() is called, passing updates when they are present.
        /// TODO(spencer): Currently also can terminate when the global inShutdown() function
        /// returns true.  Remove that once the legacy repl coordinator is gone.
        void run();

        /// Signals the run() method to terminate.
        void shutdown();

    private:
        void _resetConnection();

        /**
         * Authenticates _connection using the server's cluster-membership credentials.
         *
         * Returns true on successful authentication.
         */
        bool replAuthenticate();

        /* Sends initialization information to our sync target, also determines whether or not they
         * support the updater command.
         */
        bool replHandshake(OperationContext* txn);

        /* Inform the sync target of our current position in the oplog, as well as the positions
         * of all secondaries chained through us.
         * ErrorCodes::NodeNotFound indicates that the caller should re-run replHandshake before
         * calling this again.
         */
        Status updateUpstream(OperationContext* txn);

        bool hasConnection() {
            return _connection.get();
        }

        /// Connect to sync target.
        bool _connect(OperationContext* txn, const HostAndPort& host);

        // stores our OID to be passed along in commands
        /// TODO(spencer): Remove this once the LegacyReplicationCoordinator is gone.
        BSONObj _me;
        // the member we are currently syncing from
        HostAndPort _syncTarget;
        // our connection to our sync target
        boost::scoped_ptr<DBClientConnection> _connection;
        // protects cond, _shutdownSignaled, and the indicator bools.
        boost::mutex _mtx;
        // used to alert our thread of changes which need to be passed up the chain
        boost::condition _cond;
        // used to indicate a position change which has not yet been pushed along
        bool _positionChanged;
        // used to indicate a connection change which has not yet been shook on
        bool _handshakeNeeded;
        // Once this is set to true the _run method will terminate
        bool _shutdownSignaled;
    };
} // namespace repl
} // namespace mongo
